Rhodium(I)-catalyzed [2 + 2 + 2] cycloaddition reactions of triacetylenic 15-membered aza macrocycles: A comparative structural study

Abstract

A variety of new nitrogen-containing 15-membered triacetylenic macrocycles with one or two alkyl substituents in a propargylic position have been efficiently synthesized and completely characterized. These macrocyclic systems undergo [2 + 2 + 2] cycloaddition reactions, leading to the corresponding fused tetracycles with a benzene core on treatment with Wilkinson's catalyst, [RhCl(PPh 3) 3]. The effects of alkyl chains have been evaluated on both the efficiency of the reaction and the conformational and structural analysis of the reactants

We would like to thank the Spanish MICINN (projects CTQ2008-05409 and CTQ2011-23121), and the Generalitat de Catalunya (project 2009SGR637) for their financial support. S.B. thanks the University of Girona (UdG) for a predoctoral fellowship. Spectroscopic data have been partially funded by the University of Girona under the project with reference STR-CT00059